How to remove all private information stored by Mozilla Firefox 50.1?

After you have used Mozilla Firefox for a period of time, it will store different types of private information that you used while visiting Websites like:

Browsing History
Saved Form Information
Saved Passwords
Download History
Cookies
Cache
Authenticated Sessions

If you want to remove the recorded private information, you can follow these steps.

1. Click the "Menu > Options" icon from the top right corner of the window. You see the "about:preferences" page showing up.

2. Click the "Privacy" tab on the left side of the page. You see "Privacy" options showing up.

3. Click the "clear your recent history" link in the "History" section. You see "Clear Recent History" screen showing up.

4. Select "Everything" from the "Time range to clear" dropdown.

5. Click and open the "Details" section. Then click to select all types of private data:

[x] Browsing & Download History
[x] From & Search History
[x] Cookies
[x] Cache
[x] Active Logins
[x] Offline Website Data
[x] Site Preferences

6. Click "Clear Now" button to remove private data of all selected types.
.

⇒Install and Use Mozilla Firefox 50.1

⇒⇒Firefox - Frequently Asked Questions